First off-line tests and performance of the Notre Dame multi-reflection time-of-flight mass spectrometer

Abstract

A multi-reflection time-of-flight mass spectrometer (MR-TOF) will be a critical component for quickly removing radioactive contaminants produced at the future “N = 126 factory” addition to ATLAS at Argonne National Laboratory (ANL). This unique thermalized ion beam facility will employ multi-nucleon transfer reactions to produce very neutron-rich isotopes relevant to the astrophysical r-process. Ion beams produced at this facility will include isobaric contaminants, while precision measurements of such rare isotopes typically require highly purified samples. Hence, to tackle this issue an MR-TOF has been built and commissioned at the University of Notre Dame in an off-line test setup comprising a thermionic source and a Bradbury-Nielsen gate (BNG) to create the ions bunches to be purified. Resolving power above 30,000, with a corresponding efficiency of 35%, has been achieved. Most of the ion beam losses could be the result of the large radial divergence of ion bunches produced by the BNG, hence greater efficiency and resolving power are expected once the MR-TOF is connected to an radiofrequency quadrupole (RFQ) cooler and buncher at ANL.